1. Field of the Invention
This invention relates to tubing benders and more particularly to tubing benders capable of effecting bends in tubing of differing diameters. Specifically, it relates to improved tubing benders with improved tubing retention and handling properties.
2. Description of the Prior Art
Electricians have used portable tubing benders to bend electrical conduit. Similarly plumbers and other craftsmen have used tubing benders to bend tubing for a variety of applications. A typical tubing bender includes a mandrel having an arcuate groove or recess. The radius of the arc of the groove roughly corresponds with the radius of bend, or bending radius, to be imposed upon the tubing. The groove is typically semicircular in cross section with a radius that generally corresponds to the outside radius of the tubing, the holding radius. The mandrel is secured to a handle while a forming press having complementary surfaces is secured to a second handle and the handles are pivotally connected together. A hook arrangement, or tube retainer, is provided to retain the tubing in appropriate orientation with the groove in the mandrel as bending is effected by relatively rotating the handles such that the forming press orbits around the mandrel groove. There have been tubing benders having mandrels with sets of arcuate grooves, or tube recesses, which have different arc radii. This allows such a tubing bender to be prepared to bend tubes to different radii without assembling a new mandrel to the remainder of the bender. An example of the foregoing can be found in U.S. Pat. No. 6,487,889, which is fully incorporated herein by this reference.
While tubing benders of this type increase the flexibility for bending tubing to different radii, they still have substantial shortcomings. They are awkward to handle both while providing the necessary bending moments and during installation of tubing to be bent. While providing the bending moments, the operator frequently feels as though another hand is needed. With one hand on each handle and the tubing placed in the bender, the entire assembly becomes unwieldy when the operator must support the bender with a length of tubing inserted therein and at the same time bring the handles together to accomplish a bend with an arc of adequate precision to make the bent tube useful. Even more significant, the placement of the tube to be bent into the bender requires holding the tube in place while holding the bender, with its tendency to bend uncontrollably about the mandrel, while concurrently coping with tricky placement of the hook arrangement about the tube and, with all hands already occupied, tightening a thumbscrew to hold the hook in place that is to hold the tube in place. This clearly is job for which a juggler may be best suited.
Thus, it is highly desirable to provide a tool for bending tubing to a range of bend radii and over a range of arcs that is less clumsy both during insertion of tubing to be bent and during actual bending of the tube, allowing a quicker and more precise bending process.
Accordingly, even though portable tubing benders have been in use for a long time, there is a continuing need for such a tubing bender.